schuster



Jan. 21, 1964 e. SCHUSTER Q BELT CONTROL 4 Sheets-Sheet 1 INVENTOR 6 0mm 1. $670578? @Zgafi'lq Filed Jan. 19, 1962 Arron/5y:

United States Patent 3,118,314 BELT CGNTRGL Gordon L. Schuster, Minneapoiis, Minm, assignor to Timesavers Sanders, lino, Minneapolis, Minn, a corporation of Minnesota Filed Earl. 19, I962, Ser. No. 167,464 6 Claims. (Cl. 74-241) This invention relates to an improved construction for a belt control and more particularly to a device for maintaining a moving belt in a normal path by selectively ti'lting a roll in engagement with the belt causing the belt to return into its normal path, wherein a sensing member determining belt deviation is associated with a roll supporting the belt.

It is well recognized that a belt mounted on two or more axially parallel rolls and being driven by one of the rolls does in some instances creep away from its normal path. One solution to the problem of a belt creeping off its normal path is to tilt one of the rolls from its normal parallel position so that the belt returns to a normal path. In the prior art devices, sensing devices which determine deviation from the normal path have been placed between two rolls where the operation of the sensing devices have been satisfactory to determine deviation. However, it has been found that in instances where the belt breaks, the belt has a tendency to whip about and come into sharp engagement with the sensing devices so that the sensing device is damaged by the broken belt. Thus, such belt control devices have not met with great acceptance because of their delicacy, inasmuch as the sensitive portion of the device is often damaged when the belt breaks. It is therefore a principal object of the herein disclosed invention to provide a belt control wherein a sensing device is not liable to be damaged when a belt breaks.

It is another object of the herein disclosed invention to provide a belt control device wherein a belt may be automatically moved along a supporting roll without the use of auxiliary equipment which engages the belt and the distance between supporting rolls may be selectively varied.

A still further object of the present invention is to provide a bet control wherein the belt control keeps a belt in its normal path and small deviations from the normal path may be readily determined and corrected.

Another object of the herein disclosed invention is to provide a belt control device which is simple to manufacture and may be readily mounted in a machine using a moving belt.

Still another and more specific object of the invention is to provide a machine having a roller structure for supporting and driving a continuous belt of abrasive material or the like, with a new and improved means for automatically sensing deviation of the belt from its normal path on the roller structure and returning it thereto with the sensing means being located on or in close association with the roller structure for protection of the means against destruction or contamination as well as economy in manufacture and maintenance of the machine.

These and other more detailed and specific objects will be disclosed in the course of the following specification, reference being bad to the accompanying drawings, in which-- FIG. 1 is a plan view of a frame and a pair of rolls supporting a belt shown in dotted form and a portion of one of the rolls being broken away to show an air conduit which is a portion of the herein disclosed invention.

FIG. 2 is a side elevation of the frame and rolls shown in FIG. 1.

FIG. 3 is a cross sectional view taken on line 3-3 of FIG. 1.

Edihjii Patented Jan. 21, 1$4

FIG. 4 is a diagrammatic view showing the interrela tion of various parts of a pneumatic system which constitutes one form of this invention.

FIG. 5 is a fragmentary side elevation taken from line 55 of FIG. 4 showing in solid and broken lines two positions of the roller about its tilt axis.

FIG. 6 is a diagrammatic view of an alternate embodiment of the pneumatic roller positioning system using a single acting pneumatic jack or cylinder.

FIG. 7 is a side elevation of the alternate embodiment of the invention shown in FIG. 6 taken along line '77 of FIG. 6.

FIG. 8 is a section taken through the single acting jack of the alternate embodiment of the invention taken on line 83 of FIG. 7.

FIG. 9 is a section similar to FIG. 8 showing a different single acting jack construction for use in the alternate embodiment of the invention.

FIG. 10 is an elevation of one end of the roll showing a different sensing device construction which may be used with either embodiment of the invention.

FIG. ll is a diagrammatic view of still another and somewhat simplified form or" the pneumatic system utilizing a single acting jack such as shown in FIGS. 8 and 9.

FIG. 12 is a diagrammatic view of still another pneumatic system similar to that of FIG. 11 but utilizing an air jet and a jack at each end of the roller.

Referring now to the drawings and especially to FIG. 1, it may be seen that a portion 10 of an abrading machine is shown therein. The portion of the abrading machine generally includes a frame 12, a drive roll 14 rotatably supported in the frame, a yoke 16 pivotly supported on the frame and having its axis of rotation perpendicular to the axis of rotation of roll 14, a tilt roll 18 rotatably supported in the yoke 16, a belt Zil shown in dotted form engaging the rolls l4 and I8 and being driven by roll 1 and a control system shown partially in diagrammatic form in FIG. 4.

The frame 12 is conventional in construction in that it includes a drive roll cross bar 22 which has a pair of spacers 24 and 26 formed integral therewith, and a pivot cross bar 28 is spaced from the cross bar 22 and formed integral with the spacers 24 and 26. The frame also has a pair of pillow blocks 30 and 32 mounted on and protruding from the cross bar 22 supporting a drive shaft 3 .hich is fixed to the drive roll 14. The drive shaft is in turn connected to a source of rotating energy which is not shown in this instance.

Formed integral with bar 28 is a pivot housing 36 which rotatably supports the yoke 16 to provide for tilting of roll 18. A hollow piston 38 is slidably mounted in the housing 36 and mounted within the hollow piston is an inner roller bearing 443 which has its outer race 42 in engagement with the hollow piston 38. An inner race 44 of the bearing is in engagement with a shaft 46. An outer roller bearing 48, identical in construction to bearing 40, has an inner race 50 in engagement with the shaft 46 while an outer race 52 is in engagement with the hollow piston 33. A cylindrical spacer 54 is positioned between the outer races 42 and 48 to hold the two hearings in a spaced position.

The hollow piston 38 is connected to a means for moving the yoke and roll 1-8 relative to roll 14-. A shank 5-5 is welded to the piston 33 and the shank is pivotly attached to an arm 58 by means of a pin 66. The arm 58 has one end pivotly attached to the frame 12, inasmuch as one end is pivotly attached to a brace 62 which is fixed to bar 28 and the brace is attached to arm 58 by means of a single pin 64. The other end of arm 58 is pivotly attached to a source of energy in the form of a double acting pneumatic cylinder 66. The cylinder 66 has its rod 68 attached to a bar 70 which is pivotly attached to the other end of arm 58 by means of pin 72. The cylinder 66 is pivotly mounted on frame 12 by means of a cylinder mount 74 which is fixed to cross bar 22 and is held onto the mount by a pivot pin 76 so that the cylinder may pivot relative to the frame as the arm is pivoted about the pin 64.

The yoke 16 is fixed to the shaft 46 so that the yoke may rotate relative to the frame 12 as was mentioned above, however the rotation of the yoke with the tilt roll is limited. A shank 78 is formed integral with one edge of the yoke 16. The shank is connected to a double acting pneumatic jack or cylinder 89 which is mounted on frame 12. The cylinder 80 includes a rod 82 (FIG. 2) which has an adjustment device 84 connecting the rod to the shank 78 so that the normal position of roll 18 may be selectively positioned. The cylinder 80 provides a tilting means to rotate the yoke with the tilting roll relative to roll 14 about the axis of shaft 46 for reasons which will become apparent hereinafter.

As was mentioned above, the tilt roll 18 is rotatably mounted on yoke 16. The yoke includes a pair of pillow blocks 86 and 38 which rotatably support roll shafts 90 and 92, respectively, which in turn support roll 18. The roll 18 has an orifice 94 adjacent to one edge of the roll and a second orifice 96 adjacent to the opposite edge of the roll. These orifices are equal and are positioned adjacent to opposite edges of the roll to control the belt 20. Each of the orifice is connected to a source of air under pressure. As may be seen in FIG. 1, orifice 96 is connected to a conduit 98 which extends through shaft 92 and onto rotatable connector 100. The orifice 94 is similarly connected to a rotatable connector 102 through an identical fluid conduit 104 as may be seen in FIG. 4. The connector 102 is connected to a conventional fluid conduit 106 which conduit is connected to a pneumatic relay 108 and to a pressure regulator 110 through orifice 112 which pressure regulator is in turn connected to a source of air under pressure 114. The other connector 1% is connected to a conduit 116 which connects the orifice 96 with a pneumatic relay 118 and the pressure regulator 110 through an orifice 120. Both of the pneumatic re lays 108 and 118 are connected to the source of air under pressure 114 by a conduit 122. The relays are also connected to the cylinder 80 to control the flow of air under pressure to a selected side of the cylinder 80. Relay 108 termine the direction of the operation of the cylinder and thus the direction of the rotation of yoke 16.

In operation, portion constitutes a part of a machine, such as an abrading machine which is conventional in construction and not shown in its entirety herein inasmuch as the remainder of the machine is well known. The drive shaft 34 is connected to a conventional source of rotating energy, such as, electric motor through a series of conventional belts none of which is shown herein. The drive shaft 34 in turn turns the roll 14 which is the work roll or contact roll to drive belt 20. The tilt roll or idler roll 18 also supports the belt and is rotated by the belt in yoke 16.

The tightness of the belt is determined by the operation of cylinder 66. The tightness of the belt may be increased by applying air under pressure to cylinder 66 so that rod 68 is pushed out of the cylinder thereby pushing up on arm 58 through pin 72 so that the arm 58 pivots about pin 64. In this manner, the shank 56 is pushed toward bar 28 and pushing with it the piston 38 into housing 36. Thus, the yoke 16 along with idler roll 18 is spaced further from the work roll 14. By the same token, the belt may be loosened by applying air under pressure to the proper side of cylinder 66 to draw the idler roll 13 toward the work roll 14 through the same mechanical linkage.

The source of air under pressure 114 supplies air to pressure regulator 110. The conduits 106 and 116 have 21 A2 inside diameter, however, portions 106a and 116:: have a inside diameter, and the common portion of the conduits to the regulator has a inside diarnctcr. The gauge 128 provides a means for observing the air pressure in the portions 106:: and 116a of the fluid conduits. The air regulator is adjusted so that the pressure in the inside diameter conduit is at 20 lbs. per square inch gauge pressure. After the air leaves the respective orifices 112 and 120 and enters conduits 106 and 116, respectively, the pressure drops down to 4 lbs. per square inch gauge, so that the pressure at the orifices 94 and 96 which are Vs" in diameter is also 4 lbs. per square inch gauge pressure. The air pressure to the relays 108 and 118 is also 4 lbs. per square inch gauge pressure.

As the rolls 18 and 14 are rotating with the belt 20 riding on the rolls, the belt may creep to one side or the other so that one of the orifices is covered. In the event that orifice 94 is covered, although it is covered only through 50% of each rotation of roll 18, the pressure in the conduit 166 is increased to approximately 12 lbs. per square inch gauge. The increase in pressure is sufficiently great to actuate pneumatic relay 108. When the relay is actuated, the source of air under pressure supplies air to the relay to one side of the cylinder 80, thus moving the yoke about its axis of rotation and tilting the idler roil 18 in a proper direction to move the belt along the idler roll to return the belt to a normal path. When the orifice 94 is uncovered, the pressure in conduit 106 drops back to its normal 4 lbs. per square inch gauge and relay 108 is deencrgized, thereby cutting off the supply' of air to the cylinder 80. Should the belt 20 cover orifice 96 the pressure is raised in conduit 116 to operate relay 1118, thereby supplying air under pressure to the opposite side of cylinder 80 to tilt the roll 18 in the opposite direction and thereby cause the belt to move back to center.

Referring now to FIG. 6 a different embodiment of the invention is shown utilizing the same frame 12 and yoke 16 arrangement as shown in F1 1 through 4. Here, however, the tiltable roll designated at 18a is provided with an orifice 94a and conduit 104a which leads from the orifice to the rotatable connector 102. The pneumatic system for supplying air under pressure to the orifice 94a and for sensing an increase in pressure in conduit 104a is identical to that for orifice 94 in the embodiment hereinbefore disclosed. Accordingly, the same numbers are used for the system components. Inasmuch as the roll is provided with only one orifice only half of the system is used.

In this embodiment line 124 leads to a single acting jack which is mounted to extend between the frame 12 and shank 78 as shown in FIG. 7. The jack construction is shown in FIG. 8. Line 124 communicates with the interior of one end of the jack cylinder which carries a piston 132 connected to the shank 78 by rod 134 slidably extending through the end cover 136. A spiral spring 138 encircles rod 134 and is held under compression between the piston 132 and cover 136. Rod 134 is externally threaded with nut 140 threaded thereon for adjustment of the overall length of the jack and accordingly of the initial position of the roll 18a.

The roll 18a is so mounted and adjusted to a slightly off parallel position relative to roll 14 whereby the belt 20 can creep only in the direction of orifice 94a, the spring tensioned cylinder 130 yieldably retaining the roll in this position.

in this embodiment as the belt 20 creeps along the roll to cover or partially cover the orifice 94a there is an increase in pressure in conduit 106 to actuate the relay 108 allowing air under pressure to enter the cylinder 130 in opposition to the compressive force of the spring 138. As the air pressure overcomes the bias of the spring, the

cylinder jack is extended to tilt the yoke 16 sufiiciently to cause the belt to return to the desired central path.

It will be understood that as the belt uncovers orifice 94a the pressure in line 106 will drop to normal and the air pressure to the cylinder 130 will be terminated allowing spring 138 to return the jack to its preadjusted length with the roll returning to its original position.

The initial position of roll 18a is determined by adjustment of the nut 140. It is found that in actual operation of this embodiment it is possible to finely adjust the roll 18a to the point where the belt 20 will ride almost continuously in a position where it will partially cover the orifice 94a with the air pressure and spring Within the cylinder 130 continually balancing each other.

FIG. 9 shows a somewhat different form of jack and spring arrangement for use in the system shown in FIG. 6. Here the jack designated by the numeral 150 has a free riding piston 152 connected to the member 78 by the rod 154. Next to the jack 150 frame member 12 carries a tubular element 156 which telescopically receives a post 158 mounted on shank 78. A collar 160 is adjustable along the element 156 by set screw 162 and a compression spring 164 is disposed between the collar and member 78 to yieldably retain the members 12 and 78 in a predetermined position of separation. In this form of jack, while the spring is externally mounted, the line 124 is also connected to the jack so as to admit air under pressure to the jack in opposition to the bias of the spring means. As a component of the system the operation is the same as jack cylinder 130.

In FIG. a slightly different form of sensing device is shown which may be used with either of the pneumatic systems herein disclosed. Here a roller 18!; journaled on the yoke 16 engages the belt in the same manner as rolls 18 and 18a. In this form, however, the length of the roll is no greater than the width of belt 20. An orifice 9412, at the end of condiut 104g which is connected to line 106 by connector 103, is positioned adjacent the end of roll 18b and substantially in the plane of the outermost surface of the roll. This type of sensing device functions the same as where the orifice is built into the roll and may be used at both sides of the roll as in the system of FIG. 4 or at only one side of the roll as in the system of FIG. 6.

It will be understood, however, that the connector 103 need not be a rotary one like the connectors 102 and that the orifice will be covered by belt 20 throughout the rotation of the roller 18b when the belt has crept to that point. This type of sensing device accordingly causes a slightly faster operation of the rod tilting jack used in the pneumatic system. FIG. 10 shows the belt in its orifice covering position to actuate the pneumatic roll tilting system.

The systems shown in FIGS. 11 and 12 are in certain respects simplified over those shown in FIGS. 4 and 6 in that the pneumatic relays have been eliminated. In the system of FIG. 11 air under pressure is supplied from the source 170 to pressure regulator 171 and then into line 172 which is connected by a T coupling 174 with line 175, which leads to the roller orifice 94a and with line 176 which leads to the single acting jack 130. Line 172 has a considerably smaller diameter than lines 175 and 176 and accordingly the air pressure drops substantially as it passes through the orifices in the coupling 174. Thus in this system when the belt 20 covers the orifice 94a, the pressure will be built up in lines 175 and 176 sufliciently to activate the jack 130 and move the roller about its tilt axis until the belt 20 is recentered on the roller 18a.

The system of FIG. 12 is similar to that just described excepting that a double jet orifice roller of the type shown in FIGS. 1 to 4 is used and single acting jacks 180 and 181 are provided at each end of the yoke 16 connecting the yoke with frame 12 respectively through connection with yoke mounted shanks 182 and 183 which are similar to shank 78.

Here the air passes from the source 190 to roller orifice 94 through pressure regulator 191, line 192, an orificed T coupling 194 and line 195. Coupling 194 also connects line 192 to line 196 which leads to jack 180. Lines 19 5 and 196 are greater in diameter than line 192 so that there is a drop in air pressure as it passes the orifices of coupling 194. This pressure is insufficient to activate the jack 180. However, when the orifice 94 becomes covered the pressure buildup in lines 195 and 196, still less than that in line 192, is sufiicient to activate the jack to tilt the roller in a belt centering direction.

Jack 13d is similarly operated by air pressure from the source passing through regulator 197, line 198, orificed T coupling 199 and lines 200 and 201 respectively leading to roller orifice 96 and jack 181. Here again lines 200 and 201 are somewhat greater in diameter than line 198 causing a drop in pressure as the air passes through coupling 199. Thus when orifice 96 is covered the pressure in lines 200 and 201 will build up sufiiciently to operate jack 181 and tilt the roller in a direction opposite to that caused by operation of the jack 180. Jacks 180 and 181 may be of the type shown in FIGS. 8 and 9. However, the spring tensioning is not absolutely essential in view of the fact that the jacks conntenact one another.

vVhi'le the systems of FIGS. 11 and 12 have been shown with the rotating joints 100 and 102 and with the orifices built into the roll, it will readily be understood that the same systems can be used with the type of sensing device shown in FIG. 10.

Air pressure is found to be the most satisfactory type of fluid pressure for operation of the various types of cylinders shown. It is readily apparent, however, that rather than using an air pressure system, it would be possible to make the system operate on a vacuum rather than air pressure by a proper selection of pneumatic relays. It is further possible to provide tracking by maintaining an orifice in a closed position so that when the orifice is open the pneumatic relay operates to effect operation of the tilting means.

From the foregoing description, it is readily apparent that the present system may be easily installed in a machine which uses a wide belt. The positioning of the sensitive orifices is such that they are not readily damaged when the belt breaks. Furthermore, the device may be used to cause a constant swaying of the belt rather than a tracking by a proper selection and proper positioning of the orifices.

It is understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope of the appended claims. Having now therefore fully illustrated and described my invention, what I claim to be new and desire to protect by Letters Patent is:

1. A system for maintaining in a normal path a belt rotatably supported by one roll which is rotatably mounted in a frame, comprising in combination, a second roll rotatably and pivotly mounted on the frame and supporting said belt, tilting means mechanically connected to the second roll for tilting the roll about its pivotal mounting and relative to the first-mentioned roll, said second roll having a pair of apertures in the belt supporting surface thereof, one adjacent to each end of the roll and spaced apart a distance slightly greater than the width of the belt, an air conduit system for supplying air under a normally constant pressure to said apertures, said air conduit system including pressure responsive means connected to said apertures for detecting an increase in air pressure at each aperture, said pressure responsive means being connected to the tilting means for controlling the tilting means to tilt the second roll in one direction about the axis of its pivot mounting in response to an increase in pressure at one aperture, and in the opposite direction in response to an increase in pressure at the other aperture.

2. In a machine, a fixed frame, a first roller ournaled for rotation on said fixed frame, a secondary frame pivoted for tilting movement on the first frame on an axis perpendicular to the axis of rotation of the first roller, a second roller journaled for rotation on the secondary frame with the axis of rotation thereof nolinaliy substantially parallel to the first roller axis, a continuous belt trained about both of said rollers, spring means acting between the first and second frames for yieldably retaining the second frame in a predetermined position about said pivot axis, a pneumatic in l; connectir the first and second frames, an activatable system for su ing air under pressure to said incl; 0 vary the le thereof and move said second frame about its pivot against bias of the spring means, said system including an air outlet disposed in the periphery and adiacent one end of the second roller for activation of system as the belt moves axially along said roller over said outlet, said air outlet being at the end 'of an air passage extending into the said one end of the second roller along the axis of rotation of said roller.

3. The subject matter of claim 2 means is disposed within the jack the jack at a predetermined length.

4. A system for controlling a path of a constant Width continuous belt comprising in combination, a main frame, a first roll rotatably journaled on the frame and supporting the belt, a secondary frame pivoted to the frame on an axis perpendicular to the first roll axis of rotation, 21 second roll rotatably iournaled on the secondary frame and in engagement with the belt, the second roll having an orifice adjacent each end of its belt engaging surface, said orifices eing spaced apart a distance slightly greater than the Width of the belt, a pair of pneumatic iaclts interconnecting the frames on opposite sides of the secondary frame pivot axis and operative when actuated to move the secondary frame in opposite directions about said axis, a first air conduction means connecting one roll orifice to one jack and a second air conduction means connecting the other roll orifice to the other jack, an air pressure source, means for supplying air at a constant pressure from the air pressure source to each air conduction means whereby the pressure in either air conduction means will be increased to actuate its connected jack as its connected orifice is covered b the belt.

5. A system for maintaining in a normal path a belt driven by a drive roll which is rotatable about a fixed axis and rotatably mounted on a frail-e, comprising in wherein the spring to yieldably retain CTl combination, a second roll rotatably and pivotally mounted on the frame and supporting said belt, a pneumatic cylinder interconnecting the second roll and the frame for tilting said second roll relative to the first mentioned roll, said second roll having an orifice adjacent to one e of the roll, said second roll having an air passage extending axially into the roll from one end thereof and then radially to said orifice, an air pressure system having a source of air under pressure, a coupling, a first air conduit connecting the pressure source to the coupling, a s,eond air conduit connecting the second roll air passage to the coupling, a third air conduit connecting the pneumatic cylinder to the coupling, said coupling providin open connection between said conduits and means in said air pressure system for maintaining the pressure in the first air conduit substantially higher than the pressur in the second and third air conduits whereby movement of the belt on said second roll to cover orifice will cause an increase in pressure in the second and third air conduits to actuate said pneumatic cylin' 6. In a tracking sysetm for a machine of the character described, a main frame, a drive roll ournaled on the frame, a secondary frame pivotally mounted on the main frame, a tiltable rol journaled on the secondary frame, a pneumatically adjustable device acting between the frames for moving the secondary frame about the axis of its pivot mounting to vary the relative position of the rolls, said tiltable roll having an air outlet orifice in the circumferential Wallthercof adjacent to one end of the roll, a source of air under pressure, air conduction means having a restriction therein and having a gh pressure side connecting the source to the restriction and a low pressure side connecting the restriction to the roll orifice and said device whereby any covering of the orifice will automatically increase the pressure in the low pressure side to actuate said adjustable device.

References Cited in the file of this patent UNITED STATES PATENTS 2,199,893 Norton et al. May 7, 1940 2,613,648 Johnson Oct. 14, 1952 2,782,765 Robinson Feb. 26, V57

FOREIGN PATENTS 584,969 Germany Sept. 27, 1933 556,632 Canada Apr. 29, 1958 

5. A SYSTEM FOR MAINTAINING IN A NORMAL PATH A BELT DRIVEN BY A DRIVE ROLL WHICH IS ROTATABLE ABOUT A FIXED AXIS AND ROTATABLY MOUNTED ON A FRAME, COMPRISING IN COMBINATION, A SECOND ROLL ROTATABLY AND PIVOTALLY MOUNTED ON THE FRAME AND SUPPORTING SAID BELT, A PNEUMATIC CYLINDER INTERCONNECTING THE SECOND ROLL AND THE FRAME FOR TILTING SAID SECOND ROLL RELATIVE TO THE FIRST MENTIONED ROLL, SAID SECOND ROLL HAVING AN ORIFICE ADJACENT TO ONE EDGE OF THE ROLL, SAID SECOND ROLL HAVING AN AIR PASSAGE EXTENDING AXIALLY INTO THE ROLL FROM ONE END THEREOF AND THEN RADIALLY TO SAID ORIFICE, AN AIR PRESSURE SYSTEM HAVING A SOURCE OF AIR UNDER PRESSURE, A COUPLING, A FIRST AIR CONDUIT CONNECTING THE PRESSURE SOURCE TO THE COUPLING, A SECOND AIR CONDUIT CONNECTING THE SECOND ROLL AIR PASSAGE TO THE COUPLING, A THIRD AIR CONDUIT CONNECTING THE PNEUMATIC CYLINDER TO THE COUPLING, SAID COUPLING PROVIDING OPEN CONNECTION BETWEEN SAID CONDUITS AND MEANS IN SAID AIR PRESSURE SYSTEM FOR MAINTAINING THE PRESSURE IN THE FIRST AIR CONDUIT SUBSTANTIALLY HIGHER THAN THE PRESSURE IN THE SECOND AND THIRD AIR CONDUITS WHEREBY MOVEMENT OF THE BELT ON SAID SECOND ROLL TO COVER SAID ORIFICE WILL CAUSE AN INCREASE IN PRESSURE IN THE SECOND AND THIRD AIR CONDUITS TO ACTUATE SAID PNEUMATIC CYLINDER. 